Heat exchanger, particularly for use as a rack evaporator in refrigerators or freezers, and process for manufacturing it

Abstract: The heat exchanger is composed of a plurality of stacked shelves (2) and comprises, for each shelf, at least one coil (3) constituted by a tubular body extending along a path in which bends alternate with straight and substantially mutually co-planar portions, and a supporting and/or heat-exchange enhancing structure (5). In the heat exchanger according to the invention, the coils (3) of two contiguous shelves (2) are mutually connected by a tubular portion (4) arranged transversely with respect to the direction along which the various shelves (2) are stacked, starting from one corner of the overlying shelf down to one of the corners contiguous to the corresponding corner of the underlying shelf. The supporting and/or heat-exchange enhancing structure (5) is disconnected from the branches of the coils (3) joined to the tubular portion (4) that mutually connects two coils (3) in two different shelves (2).

Description: The present invention relates to a heat exchanger, particularly for use as a rack evaporator in refrigerators or freezers, and to a process for manufacturing it. As is known, refrigerators are generally constituted by a box-like structure having an internal chamber which is kept at a controlled temperature by means of a refrigeration circuit. In order to achieve higher efficiency of the refrigeration circuit and keep the temperature inside refrigerators as uniform as possible, rack evaporators are generally used, arranging an evaporator coil in each shelf of the refrigerator and mutually connecting the evaporator coils of the various shelves that form, as a whole, the evaporator of the circuit. More particularly, each shelf comprises a coil constituted by a tubular body extending along a path in which bends alternate with straight and substantially mutually co-planar portions, and by a supporting structure, which can be constituted by a plurality of parallel rods welded on at least one of the two faces of the coil or by a plate-like element which is seamed, welded or glued or otherwise rigidly connected to one side of the coil, has the purpose of forming a supporting surface suitable to support the products to be arranged on the shelves, and at the same time increases the heat-exchange surface of the coil. Usually, the evaporator constituted by the coils forming the various shelves of the refrigerator, as well as the portions of the evaporator that mutually connect the various coils, are formed by shaping a plurality of separate tubular bodies (coils), subsequently assembled together with the rods or with the plate, thus forming the shelf which is in turn assembled together with other shelves by welding, forming the evaporator as a whole. The evaporator, in its final configuration, is thus constituted by a plurality of coils extending along mutually parallel and superimposed planes and mutually connected by tubular portions extending vertically between the various planes. Since each shelf has a substantially rectangular shape, the evaporator substantially has, as a whole, the shape of a parallelepiped in which the tubular portions connecting the various shelves are located generally at one or more of the edges of such a parallelepiped. These known rack evaporators have some drawbacks, particularly as regards the bulk, due to the stacked arrangement of the various shelves and to the presence of the tubular portions connecting the various shelves. A rack evaporator of the type described above in fact requires very large spaces which can entail problems during packaging, shipping and possible treatments to which the evaporator must be subjected. Furthermore, in the case of evaporators constituted by a plurality of separate shelves subsequently joined in the circuit by welding, a certain defectiveness can be noted due to leakage of the refrigerating gas from defective braze welds. Alternatively, the evaporator, with its shelves and various tube portions mutually connecting them, can be formed by means of the shaping of a single tubular body, followed by the welding of rods or by the seaming of the plate for each shelf and by the final shaping of the evaporator with parallel shelves. In order to solve the drawback of bulk during packaging, shipping or treatment, in some rack evaporators the tubular portions that mutually connect the coils of the various shelves are arranged along a single edge of the parallelepipedal space occupied by the evaporator, and during packaging and shipping the shelves of other similar rack evaporators are inserted between two superimposed contiguous shelves of a same evaporator. This solution only partially solves the drawbacks linked to the packaging and shipping of rack evaporators, since the coupling of a plurality of rack evaporators significantly complicates packaging operations and makes it difficult to disengage the evaporators when they are used. Furthermore, this contrivance to reduce the overall space required by rack evaporators cannot be adopted to reduce the individual bulk of each rack evaporator during possible treatments. Furthermore, in known rack evaporators difficulties arise when bending the tubular body that constitutes the evaporator, particularly as regards the bending to which the portion connecting the coils between the various shelves must be subjected in order to always arrange this connecting portion at a single edge of the parallelepipedal space occupied by the evaporator. A rack evaporator with the features set forth in the preamble of claim 1, is known from GB-A-2.008.733. The aim of the present invention is to eliminate the above described drawbacks by providing a heat exchanger, particularly for use as a rack evaporator in refrigerators or freezers, which can have, during its possible surface treatment, its packaging and shipping, a considerably limited bulk with respect to known rack evaporators. Another object of the invention is to provide a heat exchanger which despite having a limited bulk, such as to facilitate its treatment, packaging and/or shipping, keeps unchanged the space available to support products inside a refrigerator. Another object of the invention is to provide a heat exchanger highly reliable in use. Another object of the invention is to provide a process for manufacturing heat exchangers, particularly rack evaporators, which is particularly simple and economical to perform. Another object of the invention is to provide a heat exchanger, particularly suitable to be used as a rack evaporator, which can be manufactured with a distinctly lower cost, time and defectiveness than those arising from the manufacture of known rack evaporators. With these and other objects in view, there is provided, according, to the resent invention a rack heat exchanger, as defined by the combination of features of claim 1. Further advantages of the present invention will become apparent from the following detailed description of some preferred but not exclusive embodiments thereof, illustrated only by way of non-limitative example in the accompanying drawings, wherein: figure 1 is a view of the heat exchanger according to the invention, laid out on a plane; figure 2 is a view of a different embodiment of the heat exchanger according to the invention, again laid out on a plane; figure 3 is a view of a heat exchanger of the type shown in figure 2, with the supporting and/or heat-exchange enhancing structure constituted by a plate instead of by rods; figure 4 is a view of another embodiment of the heat exchanger according to the invention, laid out on a plane; figures 5 and 6 are perspective views of two intermediate steps of the construction of the heat exchanger illustrated in figure 1; figure 7 is a lateral elevation view of the heat exchanger according to the invention, in a particular arrangement obtainable during packaging or shipping; figure 8 is an enlarged-scale perspective view of the heat exchanger illustrated in figure 1, at the end of its construction; figure 9 is an enlarged-scale perspective view of the heat exchanger illustrated in figure 3, at the end of its construction; With reference to the above figures, the heat exchanger according to the invention, generally designated by the reference numerals 1, 1a, 1b, 1c in its various embodiments, is composed of a plurality of stacked shelves 2, 2a, 2b, 2c, in which each shelf comprises a coil 3, 3a, 3b, 3c constituted by a tubular body that traces a path along which bends alternate with substantially mutually co-planar straight portions. According to the invention, the coils 3, 3a, 3b, 3c of two contiguous shelves 2, 2a, 2b, 2c are mutually connected by a tubular portion 4, 4a, 4b, 4c extending transversely to the direction along which the various shelves 2, 2a, 2b, 2c are stacked, starting from one corner of the overlying shelf down to one of the corners contiguous to the corresponding corner of the underlying shelf. More particularly, in each shelf, the coil 3, 3a, 3b, 3c lies within an ideal rectangle and the longer straight portions of the coils are arranged substantially parallel to two opposite sides of this ideal rectangle. The tubular portion 4, 4a, 4b, 4c that mutually connects two contiguous stacked coils is straight and extends along the diagonal of an ideal rectangle the corners of which are two contiguous corners of one shelf and the two corresponding corners of the overlying or underlying shelf. In practice, in a plan view of the ideal plane on which the tubular portion 4, 4a, 4b, 4c lies, the two shelves 2, 2a, 2b, 2c and the tubular portion 4, 4a, 4b, 4c that mutually connects the coils of these two shelves assume, as a whole, the shape of a letter Z. The coil 3, 3a, 3b, 3c of each shelf is connected to a supporting and/or heat-exchange enhancing structure 5, 5a, 5b, 5c which, as shown in figures 1, 2, 5, 6 and 8, can be constituted by a plurality of mutually parallel rods which are perpendicular to the longer straight portions of the coil and are connected, for example by welding, to one or both faces of the associated coil 3, 3a, 3b, 3c; as an alternative, said structure, as shown in particular in figures 3, 4 and 9, can be constituted by a plate-like element connected, for example by seaming, welding or glueing, to one of the two faces of the coil 3, 3a, 3b, 3c. As shown in the various figures, the branches of the coils joined to the portion 4, 4a, 4b, 4c that mutually connects two coils of two contiguous shelves are disconnected from the supporting and/or heat-exchange enhancing structure constituted by rods or plates so as to allow bending of this side without problems, as will become apparent hereinafter. In order to form the rack heat exchanger according to the invention, the various coils 3, 3a, 3b, 3c, as well as the tubular portions 4, 4a, 4b, 4c mutually connecting them, are formed by bending, in a single plane, a single tubular body or a plurality of mutually welded tubular bodies, as shown in particular in figures 1 to 4. The supporting structures 5, 5a, 5b, 5c are then connected to the various coils that constitute the heat exchanger according to the invention; these structures have the purpose of forming a plane suitable to support the products inside the refrigerator or freezer and at the same time of increasing the heat-exchange surface of the coils. It should be noted that connection of the supporting structures, whether constituted by a plurality of mutually parallel rods or by plate-like elements, is particularly easy even if the various coils are constituted by a single tubular body, since it can be performed on a single working surface by arranging the various coils one after the other along the same line. Furthermore, if the supporting structure is constituted by a plate, the various plates can be connected to a same face of the various coils arranged sequentially on the working surface. In the flattened arrangement, as shown in figures 1 to 4, the tubular portions 4, 4a, 4b, 4c that mutually connect the various coils 3, 3a, 3b, 3c are arranged parallel to the direction along which the various coils are arranged side by side, and more particularly they are arranged along a straight line containing one of the sides of the various shelves. The length of the tubular portion 4, 4a, 4b, 4c that mutually connects two contiguous shelves suitable to be stacked one above the other is equal to the length of the diagonal of a rectangle in which the base is the side of the shelf parallel to the tubular portion 4, 4a, 4b, 4c and the height is the desired height between two stacked contiguous shelves. According to the requirements, the tubular portion 4, 4a, 4b, 4c, in the flattened arrangement of the heat exchanger, can be parallel to the longer straight portions of each individual coil, as shown in figures 2 and 3, or can be perpendicular to the longer straight portions of each coil, as shown in figure 1. The various shelves are stacked by locking two contiguous coils 3, 3a, 3b, 3c, for example by means of clamp devices, and by moving one coil above the other by shifting it parallel to its own position. This movement stacks the shelves and produces the bending and diagonal arrangement of the tubular portions 4, 4a, 4b, 4c that connect the various coils. As an alternative, the various shelves can also be stacked by rotating one shelf, together with the portion 4, 4a, 4b, 4c that connects it to the contiguous shelf above which it must be stacked, with respect to the contiguous shelf about an axis 6 substantially coinciding with the side of the contiguous shelf directed toward the shelf which is rotated and is at right angles with respect to the portion 4, 4a, 4b, 4c that mutually connects the two shelves, and by simultaneously or subsequently rotating the shelf being considered by the same extent but in the opposite direction with respect to the portion 4, 4a, 4b, 4c that connects it to the contiguous shelf, about an axis 7 parallel to the axis 6 and substantially coinciding with the side of the shelf being considered directed toward the contiguous shelf. During packaging, surface treatment or shipping of the rack heat exchanger according to the present invention, the various shelves constituting the heat exchanger can be compacted, i.e. moved mutually closer, as shown in figure 7, by utilizing the elasticity and torsional deformability of the material of which the tubular body composing them is made. It should be noted that the torsional deformability of the coil branches connected to the tubular portion that mutually connects the coils of two shelves is facilitated by the fact that said branches are disconnected from the supporting and/or heat-exchange enhancing structure. In this manner, the rack heat exchanger according to the invention has an extremely limited bulk and facilitates packaging and shipping operations, as well as the execution of possible treatments, such as for example galvanization treatments or other treatments to which it must be subjected. In practice it has been observed that the rack heat exchanger according to the present invention fully achieves the intended aim, since the particular construction of the connection of the coils in the various shelves reduces its bulk during packaging and shipping, as well as during possible treatments, and makes it particularly easy, and feasible with modest production costs, to manufacture it. Although the heat exchanger has been conceived particularly to be used as a rack evaporator, it can nonetheless be used as heat exchanger in general with the coils arranged in horizontal, vertical or inclined planes according to the requirements. The heat exchanger thus conceived is susceptible to numerous modifications and variations, all of which are within the scope of the inventive concept; all the details may furthermore be replaced with other technically equivalent elements. In practice, the materials employed, so long as they are compatible with the specific use, as well as the dimensions, may be any according to the requirements and the state of the art. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the scope of each element identified by way of example by such reference signs.

Claims: Rack heat exchanger, particularly for use as a rack evaporator in refrigerators or freezers, composed of a plurality of stacked shelves (2,2a,2b,2c) and comprising, for each shelf, a coil (3,3a,3b,3c) constituted by at least one tubular body extending along a path to form coil branches in which bends alternate with straight and substantially mutually co-planar portions, and a supporting and/or heat-exchange enhancing structure (5,5a,5b,5c) connected to each one of said coils, the coils of two contiguous shelves being mutually connected by a tubular portion (4,4a,4b,4c) extending transversely with respect to the direction along which the various shelves are stacked, starting from one corner of the overlying shelf down to one of the corners contiguous to the corresponding corner of the underlying shelf, characterized in that at least one of the branches of each of the shelf coils (3,3a, 3b, 3c) which are joined to the respective tubular portion (4, 4a, 4b, 4c) that mutually connects the coils of two shelves are free from any rigid connection with said supporting structure (5, 5a, 5b, 5c) so as to facilitate torsion of said coil branch for formation of the rack, and respectively for allowing compaction of said rack by moving mutually closer the shelves utilizing the elasticity and torsional deformability of said coil branches. Heat exchanger according to claim 1, characterized in that, in each shelf (2,2a,2b,2c), the coil lies within an ideal rectangle. Heat exchanger according to the preceding claims, characterized in that said tubular portion (4) that mutually connects the coils (3) of two shelves (2) extends along the diagonal of an ideal rectangle the corners of which are two contiguous corners of one shelf and the two corresponding corners of the overlying or underlying shelf. Heat exchanger according to one or more of the preceding claims, characterized in that the coils (3,3a,3b,3c) of the various shelves (2,2a,2b,2c) and the tubular connecting portions are constituted by a single tubular body. Heat exchanger according to one or more of the preceding claims, characterized in that said supporting and/or heat-exchange enhancing structure (5b,5c) is constituted by a plate connected to a face of each coil (3b,3c) with the branches of the coils joined to the portion (4, 4a, 4b, 4c) that mutually connects two coils of two contiguous shelves being free from any rigid connection with said plane (5b, 5c). Heat exchanger according to one or more of the preceding claims 1 to 4, characterized in that said supporting and/or heat-exchange enhancing structure (5,5a,5b,5c) is constituted by a plurality of metal rods connected to at least one face of the associated coil (3,3a,3b,3c), said rods being arranged parallel to one another and transversely to the longer straight portions of the associated coil. Heat exchanger according to one or more of the preceding claims, characterized in that in the compacted, flattened arrangement of said heat exchanger, the tubular portions (4, 4a, 4b, 4c) are parallel to the longer straight portions of each individual coil (3, 3a, 3b, 3c), or is perpendicular to the longer straight portions of each coil (3, 3a, 3b, 3c). Process for manufacturing heat exchangers, particularly for use as rack evaporators in refrigerators and/or freezers, consisting in: -forming, by bending at least one tubular body, at least two coils (3), each of which forms a shelf (2), said coils being arranged side by side along a direction in a same plane and being mutually joined by a portion (4) of said tubular body which is substantially straight and parallel to said direction, said portion (4) substantially coinciding with an extension of a perimetric side of said shelves and having a length which is substantially equal to the length of the diagonal of an ideal rectangle in which the base is one of the sides of the shelf parallel to said direction and the height is a segment the length of which is equal to the desired distance between two contignous stacked shelves (2); connecting a supporting and/or heat-exchange enhancing structure (5) to at least one face of said coils (3), said supporting structure (5) being fixed to the branches of said coils (3) except for at least one of the branches of the coils joined to the tubular portion (4) that connects two mutually contiguous coils (3); and moving one coil (3) parallel to its original position with respect to the contiguous coil (3), so as to stack it above said contiguous coil. Process for manufacturing heat exchangers, particularly for use as rack evaporators in refrigerators and/or freezers, consisting in: -forming, by bending at least one tubular body, at least two coils (3), each of which forms a shelf (2), said coils (3) being arranged side by side along a direction in a same plane and being mutually joined by a portion (4) of said tubular body which is substantially straight and parallel to said direction, said portion (4) substantially coinciding with an extension of a perimetric side of said shelves (2) and having a length which is substantially equal to the length of the diagonal of an ideal rectangle in which the base is one of the sides of the shelf (2) parallel to said direction and the height is a segment the length of which is equal to the desired distance between two contiguous stacked shelves; connecting a supporting and/or heat-exchange enhancing structure (5) to at least one face of said coils (3), said supporting structure (5) being fixed to the branches of said coils (3) except for at least one of the branches of the coils joined to the tubular portion (4) that connects two mutually contiguous coils (3); rotating one of said two coils (3), and the tubular portion (4) connecting said two coils, with respect to the other coil (3) about a first axis (6) which is perpendicular to said portion (4) that connects the two coils (3) and substantially coincides with the side of the other coil (3) directed toward the rotated coil (3); and -rotating said one of the two coils (3), by the same extent and in the opposite direction relatively to the preceding rotation, with respect to said connecting portion about a second axis (7) parallel to said first axis (6) and substantially coinciding with the side of said one of the coils (3) directed toward said other coil (3). Process according to claim 8 or 9, characterized in that said heat exchanger is compactable by moving said stacked shelves mutually closer by utilizing the elasticity and torsional deformability of said branches of the coils joined to the tubular portion (4) that connects two mutually contiguous coils (3) which are disconnected from said supporting and/or heat-exchange enhancing structure (5).

Inventors: LOCATELLI VINCENZO, LOCATELLI, VINCENZO
Applicants: ITALIANA CONDENSER SRL, CONDENSER ITALIANA S.R.L.
Application year: 1994
Main classification: F25B39
IPC codes: F28F1, F25D25, F25B39